Railroad tank cars have long been known in railroad use in North America. This invention relates to the field of railroad tank cars and apparatus therefor. It pertains to skid and skid assemblies such as may be used to protect extending valves or drains or other fittings such as may protrude from, or stand otherwise outwardly proud of, the main cylindrical tank car tank structure. The reader may find information related to skid assemblies in U.S. Pat. No. 4,184,663 of Rollins et al., issued Jan. 22, 1980; U.S. Pat. No. 4,220,097 of Wempe et al., issued Sep. 2, 1980; U.S. Pat. No. 4,527,489 of Schlink issued Jun. 9, 1985; U.S. Pat. No. 4,697,528 of Rehbein issued Oct. 6, 1987; and U.S. Pat. No. 5,218,911 of Rehbein et al., issued Jun. 15, 1993.